Method for producing isolatable oxide microparticles or hydroxide microparticles

ABSTRACT

A method for producing isolatable oxide microparticles or hydroxide microparticles using an apparatus that processes a fluid between processing surfaces of processing members that are arranged opposite each other so as to be able to approach to or separate from each other and such that at least one can rotate relative to the other. At least two fluids are mixed and oxide microparticles or hydroxide microparticles are separated, said two fluids including: a fluid containing a microparticle raw material solution comprising a microparticle raw material mixed into a solvent, and a fluid containing a microparticle-separation solution. Immediately thereafter, the following are mixed to obtain isolatable oxide microparticles or hydroxide microparticles: a fluid containing the separated oxide microparticles or hydroxide microparticles; and a fluid containing a microparticle-treatment-substance-containing solution that contains a microparticle-treatment substance that adjusts the dispersibility of the separated oxide microparticles or hydroxide microparticles.

The present invention relates to a method for producing isolatable oxidemicroparticles or hydroxide microparticles.

BACKGROUND ART

Oxides, hydroxides, or oxides such as a hydroxylated oxide are used invarious fields; especially microparticles thereof are widely used insuch fields as an abrading agent, a catalyst, cosmetics, an electronicapparatus, a magnetic substance, a pigment and a coating material, and asemiconductor.

Oxides, hydroxides, or oxides such as a hydroxylated oxide can improvetheir properties by making them microparticles; and these microparticlesare produced generally by a sol-gel reaction or a sol-gel reactionfollowed by calcination as shown in Patent Document 1, and ahydrothermal reaction as shown in Patent Documents 2 and 3.

However, when general production methods as mentioned above are used,dispersion of oxide microparticles or hydroxide particles is poor inmany cases; especially the oxide which is produced by calcination formsa bound agglomeration of primary particles so strongly that they areoccasionally fused together. Because of this, when the oxides and thehydroxides thus produced are dispersed into various solvents or resins,they are dispersed often by mechanical grinding or mechanical crushingby using such machines as a ball mill and a bead mill. However, oxideparticles in the oxide particle dispersion solution or hydroxideparticles in the hydroxide particle dispersion solution, if theseparticles are produced, by the foregoing methods, had problems of notexpressing expected semiconductor properties, transparency,spectroscopic properties, durability, and so forth, because there is astrong force acting on particles (crystals).

Applicant of the present invention provided, as shown in Patent Document4, a method to produce oxide microparticles wherein the microparticlesare separated in a thin film fluid which is passing between processingsurfaces which are disposed in a position they are faced with eachother; but a method to produce oxide microparticles having improveddispersibility has not been disclosed specifically. Accordingly, amethod to produce oxide microparticles or hydroxide microparticleshaving improved dispersibility has been eagerly wanted.

PRIOR ART DOCUMENTS Patent Document

Patent Document 1: Japanese Patent Laid-Open Publication No. 2010-105892

Patent Document 2: Japanese Patent Application Publication No.1998-510238

Patent Document 3: Japanese Patent Laid-Open Publication No. 1993-147943

Patent Document 4: International Patent Laid-Open Publication No.009/008392

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

The present invention is made to solve the problems as mentioned above;and thus, the object thereof is to provide a method for producingisolatable oxide microparticles or hydroxide microparticles.

Means for Solving the Problems

Inventors of the present invention carried out an extensiveinvestigation, and as a result, they found that isolatable oxidemicroparticles or hydroxide microparticles can be obtained by a methodwherein a fluid which contains a microparticle raw material solutionobtained by mixing this microparticle raw material with a solvent ismixed with a fluid which contains a microparticle-separating solutionbetween at least two processing surfaces which are disposed in aposition they are faced with each other so as to be able to approach toand separate from each other, at least one of which rotates relative tothe other, thereby separating oxide microparticles or hydroxidemicroparticles, and then, a dispersion solution of the separated oxidemicroparticles or hydroxide microparticles is mixed with a fluid whichcontains a microparticle-treating substance solution obtained by mixinga microparticle-treating substance with a solvent.

An invention according to claim 1 of the present application relates toa method for producing isolatable oxide microparticles or hydroxidemicroparticles, wherein each of (I) a microparticle raw materialsolution which is obtained by mixing at least one microparticle rawmaterial with a solvent, (II) a microparticle-separating solution, and(III) a microparticle-treating substance solution which is obtained bymixing at least one microparticle-treating substance with a solvent isprepared, wherein the method comprises:

(IV) a step of separating oxide microparticles or hydroxidemicroparticles, wherein

at least two fluids to be processed are used:

out of them, at least one fluid is the fluid which contains themicroparticle raw material solution and at least one fluid other thanthe microparticle raw material solution is the fluid which contains themicroparticle-separating solution, wherein the fluid which contains themicroparticle raw material solution is mixed with the fluid whichcontains the microparticle-separating solution in a thin film fluidformed between at least two processing surfaces which are disposed in aposition they are faced with each other so as to be able to approach toand separate from each other, at least one of which rotates relative tothe other, and

(V) a step of mixing a fluid which contains the oxide microparticles orthe hydroxide microparticles separated in the step (IV) with the fluidwhich contains the microparticle-treating substance solution, wherein

the microparticle-treating substance is a substance which controlsdispersibility of the said separated oxide maicroparticles or hydroxidemicroparticles.

An invention according to claim 2 of the present application providesthe method for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 1, wherein

any one of the fluid which contains the microparticle raw materialsolution and the fluid which contains the microparticle-separatingsolution passes between the processing surfaces with forming the thinfilm fluid,

a separate introduction path independent of a flow path through whichany one of the fluids passes is arranged,

at least any one of the at least two processing surfaces is providedwith an opening to the introduction path,

any other one of the fluid which contains the microparticle raw materialsolution and the fluid which contains the microparticle-separatingsolution is introduced between the processing surfaces through theopening, whereby mixing the fluid which contains the microparticle rawmaterial solution with the fluid which contains themicroparticle-separating solution in the thin film fluid.

An invention according to claim 3 of the present application providesthe method for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 1 or 2, wherein the method comprises:

a step of separating oxide microparticles or hydroxylated oxidemicroparticles by mixing the fluid which contains the microparticle rawmaterial solution with the fluid which contains themicroparticle-separating solution in the thin film fluid formed betweenat least two processing surfaces which are disposed in a position theyare faced with each other so as to be able to approach to and separatefrom each other, at least one of which rotates relative to the other,and

a step of mixing the fluid which contains the oxide microparticles orthe hydroxide microparticles separated in the above-mentioned step withthe fluid which contains the microparticle-treating substance solution,wherein these steps are carried out continuously.

An invention according to claim 4 of the present application providesthe method for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 3, wherein

at least any one of the at least two processing surfaces is providedwith an opening to introduce the fluid which contains themicroparticle-treating substance solution between the processingsurfaces,

the fluid which contains the microparticle raw material solution ismixed with the fluid which contains the microparticle-separatingsolution in the thin film fluid to separate oxide microparticles orhydroxide microparticles, and thereafter,

the microparticle-treating substance is contacted with and acted to theseparated oxide microparticles or hydroxide microparticles in the thinfilm fluid.

An invention according to claim 5 of the present application providesthe method for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 3, wherein

an opening to supply the fluid which contains the microparticle-treatingsubstance solution is arranged in a position to face a discharge part ofthe at least two processing surfaces,

the fluid which contains the microparticle raw material solution ismixed with the fluid which contains the microparticle-separatingsolution in the thin film fluid to separate the oxide microparticles orthe hydroxide microparticles thereby discharging the fluid whichcontains the oxide microparticles or the hydroxide microparticlesthrough the discharge part, and immediately thereafter,

the microparticle-treating substance is contacted with and acted to theseparated oxide microparticles or hydroxide microparticles.

An invention according to claim 6 of the present application providesthe method for producing isolatable oxide microparticles or hydroxidemicroparticles according to any of claims 1 to 5, wherein a step ofmixing the fluid which contains the separated oxide microparticles orhydroxide microparticles with the fluid which contains themicroparticle-treating substance solution is carried out within onesecond after the step of separating the oxide microparticles or thehydroxide microparticles.

An invention according to claim 7 of the present application providesthe method for producing isolatable oxide microparticle or hydroxidemicroparticle according to any of claims 1 to 6, wherein dispersibilityof the oxide microparticles or the hydroxide microparticles iscontrolled by controlling concentration of the microparticle-treatingsubstance in the microparticle-treating substance solution that iscontacted with and acted to the separated oxide microparticles orhydroxide microparticles.

An invention according to claim 8 of the present application providesthe method for producing isolatable oxide microparticles or hydroxidemicroparticles according to any of claims 1 to 7, wherein themicroparticle-treating substance is an acidic substance or a hydrogenperoxide.

Advantages

According to the present invention, isolatable oxide microparticles orhydroxide microparticles can be obtained more readily with a lowerenergy and a lower cost than ever so that isolatable oxidemicroparticles or hydroxide microparticles can be provided cheaply andstably.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view showing the fluid processingapparatus according to an embodiment of the present invention.

FIG. 2(A) is a schematic plane view of the first processing surface inthe fluid processing apparatus shown in FIG. 1, and FIG. 2(B) is anenlarged view showing an important part of the processing surface in theapparatus.

FIG. 3(A) is a sectional view of the second introduction member of theapparatus, and FIG. 3(B) is an enlarged view showing an important partof the processing surface for explaining the second introduction member.

FIG. 4 These drawings show schematic sectional views of one example ofan apparatus arranged in the fluid processing apparatus shown in FIG. 1,wherein with this apparatus the microparticle-treating substance iscontacted with and acted to the oxide microparticles or the hydroxidemicroparticles which are separated between the processing surfaces ofthe said apparatus, wherein (A) shows the apparatus that is providedwith a supplying apparatus of the fluid which contains themicroparticle-treating substance solution, (B) shows the apparatus thatis provided with a flow path through which the dispersion solution ofthe separated oxide microparticles or hydroxide microparticles passes asa converged stream as well as with a charging hole for the fluid whichcontains the microparticle-treating substance solution, and (C) showsthe apparatus that is provided with a third introduction part tointroduce the fluid which contains the microparticle-treating substancesolution into the apparatus.

FIG. 5 These show (A) a TEM picture of microparticles of theyttria-stabilized zirconia hydrate before heat treatment and (B) a TEMpicture of microparticles of the yttria-stabilized zirconia after heattreatment (these microparticles were prepared in Example 1 of thepresent invention).

FIG. 6 These show (A) a TEM picture of microparticles of theyttria-stabilized zirconia hydrate before heat treatment and (B) a TEMpicture of microparticles of the yttria-stabilized zirconia after heattreatment (these microparticles were prepared in Example 2 of thepresent invention).

FIG. 7 These show (A) a TEM picture of microparticles of theyttria-stabilized zirconia hydrate before heat treatment and (B) a TEMpicture of microparticles of the yttria-stabilized zirconia after heattreatment (these microparticles were prepared in Comparative Example 1of the present invention).

FIG. 8 This shows a TEM picture of microparticles of the magnesium oxideafter heat treatment (the microparticles were prepared in Example 3 ofthe present invention).

FIG. 9 This shows a TEM picture of microparticles of the magnesium oxideafter heat treatment (the microparticles were prepared in ComparativeExample 2 of the present invention).

FIG. 10 This shows a TEM picture of microparticles of the titaniumdioxide (the microparticles were prepared in Example 6 of the presentinvention).

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, detailed explanation of the present invention will be made;but a technical range of the present invention is not limited by thefollowing Embodiments and Examples.

Although there is no particular restriction as to oxide or hydroxide ofthe present invention, such as for example, metal oxide or non-metaloxide having the formula of M_(x)O_(y), metal hydroxide or a non-metalhydroxide having the formula of M_(p)(OH)_(q), metal hydroxide oxide ornon-metal hydroxide oxide having the formula of M_(r)(OH)_(s)O_(t),various solvated forms of them, composition containing these substancesas main components, and so forth may be mentioned (in the formulae, eachof x, y, p, q, r, s, and t is an arbitrary integer). The oxide, thehydroxide or the hydroxide oxide includes peroxide, superoxide, and soforth.

The metal or the non-metal which constitutes the foregoing oxides andhydroxides is not particularly restricted; and thus, all elements in theperiodic table may be used. An illustrative example of the metal elementincludes Ti, Fe, W, Pt, Au, Cu, Ag, Pd, Ni, Mn, Co, Ru, V, Zn, and Zr;and an illustrative example of the non-metal element includes B, Si, Ge,N, and C. These elements may form an oxide, a hydroxide, or ahydroxylated oxide singly or in a combination of plurality of theseelements (composite oxide, composite hydroxide, and compositehydroxylated oxide).

Although there is no particular restriction as to the metal oxide or thenon-metal oxide having the formula of M_(x)O_(y) in the presentinvention, such as for example, TiO₂, SnO, SnO₂, Al₂O₃, SiO₂, ZnO, CoO,CO₃O₄, Cu₂O, CuO, Ni₂O₃, NiO, MgO, Y₂O₃, VO, VO₂, V₂O₃, V₂O₅, MnO, MnO₂,CdO, ZrO₂, PdO, PdO₂, MoO₃, MoO₂, Cr₂O₃, CrO₃, In₂O₃, or RuO₂ may bementioned.

Although there is no particular restriction as to the metal hydroxide orthe non-metal hydroxide having the formula of M_(p)(OH)_(q) in thepresent invention, such as for example, Sn(OH)₂, Sn(OH)₄, Al(OH)₃,Si(OH)₄, Zn(OH)₂, Co(OH)₂, Co(OH)₃, CuOH, Cu(OH)₂, Ni(OH)₃, Ni(OH)₂,Mg(OH)₂, Y(OH)₃, V(OH)₂, V(OH)₄, V(OH)₃, Mn(OH)₂, Mn(OH)₄, Cd(OH)₂,Zr(OH)₄, Pd(OH)₂, Pd(OH)₄, Mo(OH)₄, Cr(OH)₃, and Ru(OH)₄ may bementioned. Although there is no particular restriction in the metalhydroxide oxide or the non-metal hydroxide oxide having the formula ofM_(r)(OH)_(s)O_(t), FeOOH, MnOOH, NiOOH, AlOOH, and so forth may bementioned.

The term “isolatable” in the present invention means that particles inthe state of agglomeration can be dispersed, or that fusion of particlesafter calcination treatment can be suppressed. Accordingly, this meansthat dispersibility of the obtained oxide microparticles or hydroxidemicroparticles into a solvent or a resin is improved.

The microparticle raw material solution in the present invention is notparticularly restricted as far as at least one kind of the microparticleraw material is mixed with a solvent. As to the microparticle rawmaterial in the present invention, a metal, a non-metal, or a compoundof them may be used. The metal or the non-metal is not particularlyrestricted; and thus, all elements including a single body or an alloythereof may be used. The compound in the present invention is notparticularly restricted, while an illustrative example thereof includesthe foregoing metals or non-metals in a form of a salt, an oxide, anitride, a carbide, a complex, an organic salt, an organic complex, andan organic compound.

Although there is no particular restriction as to the metal salt or thenon-metal salt, nitrate, nitrite, sulfate, sulfite, formate, acetate,phosphate, phosphite, hypophosphite, chloride, oxychloride,acetylacetonate, and so forth of the metals or the non-metals may bementioned. Although there is no particular restriction as to the metalnitride of the present invention, such as for example, boron nitride(BN), carbon nitride (C₃N₄), silicon nitride (Si₃N₄), gallium nitride(GaN), indium nitride (InN), aluminum nitride (AlN), chromium nitride(Cr₂N) copper nitride (Cu₃N), iron nitride (Fe₄N), iron nitride (Fe₃N),lanthanum nitride (LaN), lithium nitride (Li₃N), magnesium nitride(Mg₃N₂), molybdenum nitride (Mo₂N) niobium nitride (NbN), tantalumnitride (TaN), titanium nitride (TiN), tungsten nitride (W₂N), tungstennitride (WN₂), yttrium nitride (YN), and zirconium nitride (ZrN) may bementioned. Although there is no particular restriction in the metalcarbide of the present invention, such as for example, calcium carbide(CaC₂), silicon carbide (SiC), boron carbide (B₄C), tungsten carbide(WC), tungsten carbide (W₂C), titanium carbide (TiC), zirconium carbide(ZrC), and vanadium carbide (VC_(x)) may be mentioned.

The present invention may be carried out by mixing the foregoingmicroparticle raw material with a solvent, or preferably by dissolvingor molecular-dispersing the said microparticles. Depending on thepurpose, the microparticle raw material may be selected, as appropriate,singly or a plurality of them to carry out the present invention.

An illustrative example of the solvent to mix, dissolve ormolecular-disperse the microparticle raw material includes water, anorganic solvent, or a mixed solvent comprising a plurality of them. Anillustrative example of the water includes tap water, ion-exchangedwater, pure water, ultrapure water, and RO water. An illustrativeexample of the organic solvent includes an alcohol compound solvent, anamide compound solvent, a ketone compound solvent, an ether compoundsolvent, an aromatic compound solvent, carbon disulfide, an aliphaticcompound solvent, a nitrile compound solvent, a sulfoxide compoundsolvent, a halogen-containing compound solvent, an ester compoundsolvent, an ionic liquid, a carboxylic acid compound, and a sulfonicacid compound. These solvents may be used separately or as a mixture ofa plurality of them.

In addition, the present invention may be carried out by mixing ordissolving a basic substance or an acidic substance in the foregoingsolvents in the range not adversely affecting separation of the oxidemicroparticles or the hydroxide microparticles. An illustrative exampleof the basic substance includes a metal hydroxide such as sodiumhydroxide and potassium hydroxide; a metal alkoxide such as sodiummethoxide and sodium isopropoxide; and an amine compound such astriethylamine, diethylamino ethanol, and diethylamine. An illustrativeexample of the acidic substance includes an inorganic acid such as aquaregia, hydrochloric acid, nitric acid, fuming nitric acid, sulfuricacid, and fuming sulfuric acid; and an organic acid such as formic acid,acetic acid, chloroacetic acid, dichloroacetic acid, oxalic acid,trifluoroacetic acid, trichloroacetic acid, and citric acid. These basicor acidic substances may be used as a mixture with the various solventsas mentioned above, or each of the substances may be used separately.These basic or acidic substances may be used after they are mixed withvarious solvents in advance, as mentioned above to carryout the presentinvention; or they may be used by mixing these basic or acidicsubstances with the foregoing solvents just before separation of theoxide microparticles or the hydroxide microparticles by using respectiveseparate and independent flow paths as mentioned later.

To explain the foregoing solvents in more detail, an illustrativeexample of the alcohol compound solvent includes a linear alcohol suchas methanol, ethanol, n-propanol and n-butanol; a branched alcohol suchas isopropanol, 2-butanol, tert-butanol and 1-methoxy-2-propanol; and apolyvalent alcohol such as ethylene glycol and diethylene glycol. Anillustrative example of the ketone compound solvent includes acetone,methyl ethyl ketone, and cyclohexanone. An illustrative example of theether compound solvent includes dimethyl ether, diethyl ether,tetrahydrofuran and propylene glycol monomethyl ether. An illustrativeexample of the aromatic compound solvent includes nitrobenzene,chlorobenzene, and dichlorobenzene. An illustrative example of thealiphatic compound solvent includes hexane. An illustrative example ofthe nitrile compound solvent includes acetonitrile. An illustrativeexample of the sulfoxide compound solvent includes dimethyl sulfoxide,diethyl sulfoxide, hexamethylene sulfoxide, and sulfolane. Anillustrative example of the halogen-containing compound solvent includeschloroform, dichloromethane, trichloroethylene, and iodoform. Anillustrative example of the ester compound solvent includes ethylacetate, butyl acetate, methyl lactate, ethyl lactate, and2-(1-methoxy)propyl acetate. An illustrative example of the ionic liquidincludes a salt of 1-butyl-3-methyl imidazolium withPF6-(hexafluorophosphate ion). An illustrative example of the amidecompound solvent includes N,N-dimethylformamide, 1-methyl-2-pyrrolidone,2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone,ε-caprolactam, formamide, N-methyl formamide, acetamide,N-methylacetamide, N,N-dimethylacetamide, N-methylpropaneamide, andhexamethylphosphoric triamide. An illustrative example of the carboxyliccompound includes 2,2-dichloropropionic acid and squaric acid. Anillustrative example of the sulfonic acid compound includesmethanesulfonic acid, p-toluenesulfonic acid, chlorosulfonic acid, andtrifluoromethane sulfonic acid.

As to the microparticle-separating solution to separate the oxidemicroparticles or the hydroxide microparticles by mixing with themicroparticle raw material solution, the same solvents as thosementioned above may be used. A solvent to mix, or preferably to dissolveor to molecular-disperse these microparticles, and a solvent to separatethese microparticles are selected depending on the intended oxide,hydroxide, or hydroxylated oxide to carry out the present invention. Inthe microparticle-separating solution of the present invention, theabove-mentioned solvents may be used singly or as a mixture of pluralityof them; and in addition, these solvents may contain the foregoingacidic or basic substances.

To carryout the present invention, it is preferable that mixing of thefluid which contains the microparticle raw material solution with thefluid which contains the microparticle-separating solution be done bystirring and uniformly mixing these fluids in a thin film fluid formedbetween processing surfaces which are disposed in a position they arefaced with each other so as to be able to approach to and separate fromeach other, at least one of which rotates relative to the other. As tothe apparatus like this, for example, an apparatus based on the sameprinciple as the one that is disclosed in Patent Document 4 which wasfiled by the present applicant may be used. By using the apparatus basedon the principle like this, the isolatable oxide microparticles orhydroxide microparticles can be produced.

Hereinafter, embodiments of the above-mentioned apparatus will beexplained by using the drawings.

The fluid processing apparatus shown in FIG. 1 to FIG. 3 is similar tothe apparatus described in Patent Document 4, with which a material tobe processed is processed between processing surfaces in processingmembers arranged so as to be able to approach to and separate from eachother, at least one of which rotates relative to the other; wherein, ofthe fluids to be processed, a first fluid to be processed, i.e., a firstfluid, is introduced into between the processing surfaces, and a secondfluid to be processed, i.e., a second fluid, is introduced into betweenthe processing surfaces from a separate path that is independent of theflow path introducing the afore-mentioned fluid and has an openingleading to between the processing surfaces, whereby the first fluid andthe second fluid are mixed and stirred between the processing surfaces.Meanwhile, in FIG. 1, a reference character U indicates an upside and areference character S indicates a downside; however, up and down, frontand back and right and left shown therein indicate merely a relativepositional relationship and does not indicate an absolute position. InFIG. 2(A) and FIG. 3(B), reference character R indicates a rotationaldirection. In FIG. 3(C), reference character C indicates a direction ofcentrifugal force (a radial direction).

In this apparatus provided with processing surfaces arranged opposite toeach other so as to be able to approach to and separate from each other,at least one of which rotates relative to the other, at least two kindsof fluids as fluids to be processed are used, wherein at least one fluidthereof contains at least one kind of material to be processed, a thinfilm fluid is formed by converging the respective fluids between theseprocessing surfaces, and the material to be processed is processed inthis thin film fluid. With this apparatus, a plurality of fluids to beprocessed may be processed as mentioned above; but a single fluid to beprocessed may be processed as well.

This fluid processing apparatus is provided with two processing membersof a first processing member 10 and a second processing member 20arranged opposite to each other, wherein at least one of theseprocessing members rotates. The surfaces arranged opposite to each otherof the respective processing members 10 and 20 are made to be therespective processing surfaces. The first processing member 10 isprovided with a first processing surface 1 and the second processingmember 20 is provided with a second processing surface 2.

The processing surfaces 1 and 2 are connected to a flow path of thefluid to be processed and constitute part of the flow path of the fluidto be processed. Distance between these processing surfaces 1 and 2 canbe changed as appropriate; and thus, the distance thereof is controlledso as to form a minute space usually in the range of 1 mm or less, forexample, 0.1 μm to 50 μm. With this, the fluid to be processed passingthrough between the processing surfaces 1 and 2 becomes a forced thinfilm fluid forced by the processing surfaces 1 and 2.

When a plurality of fluids to be processed are processed by using thisapparatus, the apparatus is connected to a flow path of the first fluidto be processed whereby forming part of the flow path of the first fluidto be processed; and part of the flow path of the second fluid to beprocessed other than the first fluid to be processed is formed. In thisapparatus, the two paths converge into one, and two fluids to beprocessed are mixed between the processing surfaces 1 and 2 so that thefluids may be processed by reaction and so on. It is noted here that theterm “process(ing)” includes not only the embodiment wherein a materialto be processed is reacted but also the embodiment wherein a material tobe processed is only mixed or dispersed without accompanying reaction.

To specifically explain, this apparatus is provided with a first holder11 for holding the first processing member 10, a second holder 21 forholding the second processing member 20, a surface-approaching pressureimparting mechanism, a rotation drive mechanism, a first introductionpart d1, a second introduction part d2, and a fluid pressure impartingmechanism p.

As shown in FIG. 2(A), in this embodiment, the first processing member10 is a circular body, specifically a disk with a ring form. Similarly,the second processing member 20 is a circular disk. Material of theprocessing members 10 and 20 is not only metal and carbon but alsoceramics, sintered metal, abrasion-resistant steel, sapphire, and othermetal subjected to hardening treatment, and rigid material subjected tolining, coating, or plating. In the processing members 10 and 20 of thisembodiment, at least part of the first and the second surfaces 1 and 2arranged opposite to each other is mirror-polished.

Roughness of this mirror polished surface is not particularly limited;but surface roughness Ra is preferably 0.01 μm to 1.0 μm, or morepreferably 0.03 μm to 0.3 μm.

At least one of the holders can rotate relative to the other holder by arotation drive mechanism such as an electric motor (not shown indrawings). A reference numeral 50 in FIG. 1 indicates a rotary shaft ofthe rotation drive mechanism; in this embodiment, the first holder 11attached to this rotary shaft 50 rotates, and thereby the firstprocessing member 10 attached to this first holder 11 rotates relativeto the second processing member 20. As a matter of course, the secondprocessing member 20 may be made to rotate, or the both may be made torotate. Further in this embodiment, the first and second holders 11 and21 may be fixed, while the first and second processing members 10 and 20may be made to rotate relative to the first and second holders 11 and21.

At least any one of the first processing member 10 and the secondprocessing member 20 is able to approach to and separate from at leastany other member, thereby the processing surfaces 1 and 2 are able toapproach to and separate from each other.

In this embodiment, the second processing member 20 approaches to andseparates from the first processing member 10, wherein the secondprocessing member 20 is accepted in an accepting part 41 arranged in thesecond holder 21 so as to be able to rise and set. However, as opposedto the above, the first processing member 10 may approach to andseparate from the second processing member 20, or both the processingmembers 10 and 20 may approach to and separate from each other.

This accepting part 41 is a concave portion for mainly accepting thatside of the second processing member 20 opposite to the secondprocessing surface 2, and this concave portion is a groove being formedinto a circle, i.e., a ring when viewed in a plane. This accepting part41 accepts the second processing member 20 with sufficient clearance sothat the second processing member 20 may rotate. Meanwhile, the secondprocessing member 20 may be arranged so as to be movable only parallelto the axial direction; alternatively, the second processing member 20may be made movable, by making this clearance larger, relative to theaccepting part 41 so as to make the center line of the processing member20 inclined, namely unparallel, to the axial direction of the acceptingpart 41, or movable so as to depart the center line of the processingmember 20 and the center line of the accepting part 41 toward the radiusdirection.

It is preferable that the second processing member 20 be accepted by afloating mechanism so as to be movable in the three dimensionaldirection, as described above.

The fluids to be processed are introduced into between the processingsurfaces 1 and 2 from the first introduction part dl and the secondintroduction part d2, the flow paths through which the fluids flow,under the state that pressure is applied thereto by a fluid pressureimparting mechanism p consisting of various pumps, potential energy, andso on. In this embodiment, the first introduction part d1 is a patharranged in the center of the circular, second holder 21, and one endthereof is introduced into between the processing surfaces 1 and 2 frominside the circular, processing members 10 and 20. Through the secondintroduction part d2, the first fluid to be processed and the secondfluid to be processed for reaction are introduced into between theprocessing surfaces 1 and 2. In this embodiment, the second introductionpart d2 is a path arranged inside the second processing member 20, andone end thereof is open at the second processing surface 2. The firstfluid to be processed which is pressurized with the fluid pressureimparting mechanism p is introduced from the first 10 and 20 so as topass through between the first and processing surfaces 1 and 2 tooutside the processing members 10 and 20. From the second introductionpart d2, the second fluid to be processed which is pressurized with thefluid pressure imparting mechanism p is provided into between theprocessing surfaces 1 and 2, whereat this fluid is converged with thefirst fluid to be processed, and there, various fluid processing such asmixing, stirring, emulsification, dispersion, reaction, deposition,crystallization, and separation are effected, and then the fluid thusprocessed is discharged from the processing surfaces 1 and 2 to outsidethe processing members 10 and 20. Meanwhile, an environment outside theprocessing members 10 and 20 may be made negative pressure by a vacuumpump.

The surface-approaching pressure imparting mechanism mentioned abovesupplies the processing members with force exerting in the direction ofapproaching the first processing surface 1 and the second processingsurface 2 each other. In this embodiment, the surface-approachingpressure imparting mechanism is arranged in the second holder 21 andbiases the second processing member 20 toward the first processingmember 10.

The surface-approaching pressure imparting mechanism is a mechanism togenerate force (hereinafter, surface-approaching pressure) to press thefirst processing surface 1 of the first processing member 10 and thesecond processing surface 2 of the second processing member 20 in thedirection to make them approach to each other. The mechanism generates athin film fluid having minute thickness in a level of nanometer ormicrometer by the balance between the surface-approaching pressure andthe force to separate the processing surfaces 1 and 2 from each other,i.e., the force such as the fluid pressure. In other words, the distancebetween the processing surfaces 1 and 2 is kept in a predeterminedminute distance by the balance between these forces.

In the embodiment shown in FIG. 1, the surface-approaching pressureimparting mechanism is arranged between the accepting part 41 and thesecond processing member 20. Specifically, the surface-approachingpressure imparting mechanism is composed of a spring 43 to bias thesecond processing member 20 toward the first processing member 10 and abiasing-fluid introduction part 44 to introduce a biasing fluid such asair and oil, wherein the surface-approaching pressure is provided by thespring 43 and the fluid pressure of the biasing fluid. Thesurface-approaching pressure may be provided by any one of this spring43 and the fluid pressure of this biasing fluid; and other forces suchas magnetic force and gravitation may also be used. The secondprocessing member 20 recedes from the first processing member 10 therebymaking a minute space between the processing surfaces 1 and 2 byseparating force, caused by viscosity and the pressure of the fluid tobe processed applied by the fluid pressure imparting mechanism p,against the bias of this surface-approaching pressure impartingmechanism. By this balance between the surface-approaching pressure andthe separating force as mentioned above, the first processing surface 1and the second processing surface 2 can be set with the precision of amicrometer level; and thus the minute space between the processingsurfaces 1 and 2 may be set. The separating force mentioned aboveincludes fluid pressure and viscosity of the fluid to be processed,centrifugal force by rotation of the processing members, negativepressure when negative pressure is applied to the biasing-fluidintroduction part 44, and spring force when the spring 43 works as apulling spring. This surface-approaching pressure imparting mechanismmay be arranged also in the first processing member 10, in place of thesecond processing member 20, or in both the processing members.

To specifically explain the separation force, the second processingmember 20 has the second processing surface 2 and a separationcontrolling surface 23 which is positioned inside the processing surface2 (namely at the entering side of the fluid to be processed into betweenthe first and second processing surfaces 1 and 2) and next to the secondprocessing surface 2. In this embodiment, the separation controllingsurface 23 is an inclined plane, but may be a horizontal plane. Thepressure of the fluid to be processed acts to the separation controllingsurface 23 to generate force directing to separate the second processingmember 20 from the first processing member 10. Therefore, the secondprocessing surface 2 and the separation controlling surface 23constitute a pressure receiving surface to generate the separationforce.

In the example shown in FIG. 1, an approach controlling surface 24 isformed in the second processing member 20. This approach controllingsurface 24 is a plane opposite, in the axial direction, to theseparation controlling surface 23 (upper plane in FIG. 1) and, by actionof pressure applied to the fluid to be processed, generates force ofapproaching the second processing member 20 toward the first processingmember 10.

Meanwhile, the pressure of the fluid to be processed exerted on thesecond processing surface 2 and the separation controlling surface 23,i.e., the fluid pressure, is understood as force constituting an openingforce in a mechanical seal. The ratio (area ratio A1/A2) of a projectedarea A1 of the approach controlling surface 24 projected on a virtualplane perpendicular to the direction of approaching and separating theprocessing surfaces 1 and 2, that is, in the direction of rising andsetting of the second processing member 20 (axial direction in FIG. 1),to a total area A2 of the projected area of the second processingsurface 2 of the second processing member 20 and the separationcontrolling surface 23 projected on the virtual plane is called asbalance ratio K, which is important for control of the opening force.This opening force can be controlled by the pressure of the fluid to beprocessed, i.e., the fluid pressure, by changing a balance line, i.e.,by changing the area A1 of the approach controlling surface 24.

Sliding surface actual surface pressure P, i.e., the fluid pressure outof the surface-approaching pressures, is calculated according to thefollowing equation:P=P1×(K−k)+Ps

Here, P1 represents the pressure of a fluid to be processed, i.e., thefluid pressure, K represents the balance ratio, k represents an openingforce coefficient, and Ps represents a spring and back pressure.

By controlling this balance line to control the sliding surface actualsurface pressure P, the space between the processing surfaces 1 and 2 isformed as a desired minute space, thereby forming a fluid film of thefluid to be processed so as to make the processed substance such as aproduct fine and to effect uniform processing by reaction.

Meanwhile, the approach controlling surface 24 may have a larger areathan the separation controlling surface 23, though this is not shown inthe drawing.

The fluid to be processed becomes a forced thin film fluid by theprocessing surfaces 1 and 2 that keep the minute space therebetween,whereby the fluid is forced to move out from the circular, processingsurfaces 1 and 2. However, the first processing member 10 is rotating;and thus, the mixed fluid to be processed does not move linearly frominside the circular, processing surfaces 1 and 2 to outside thereof, butdoes move spirally from the inside to the outside thereof by a resultantvector acting on the fluid to be processed, the vector being composed ofa moving vector toward the radius direction of the circle and a movingvector toward the circumferential direction.

Meanwhile, a rotary shaft 50 is not only limited to be placedvertically, but may also be placed horizontally, or at a slant. This isbecause the fluid to be processed is processed in a minute space betweenthe processing surfaces 1 and 2 so that the influence of gravity can besubstantially eliminated. In addition, this surface-approaching pressureimparting mechanism can function as a buffer mechanism ofmicro-vibration and rotation alignment by concurrent use of theforegoing floating mechanism with which the second processing member 20may be held displaceably.

In the first and second processing members 10 and 20, the temperaturethereof may be controlled by cooling or heating at least any one ofthem; in FIG. 1, an embodiment having temperature regulating mechanismsJ1 and J2 in the first and second processing members 10 and 20 is shown.Alternatively, the temperature may be regulated by cooling or heatingthe introducing fluid to be processed. These temperatures may be used toseparate the processed substance or may be set so as to generate Benardconvection or Marangoni convection in the fluid to be processed betweenthe first and second processing surfaces 1 and 2.

As shown in FIG. 2, in the first processing surface 1 of the firstprocessing member 10, a groove-like concave portion 13 extended towardan outer side from the central part of the first processing member 10,namely in a radius direction, may be formed. The concave portion 13 maybe, as a plane view, curved or spirally extended on the first processingsurface 1 as shown in FIG. 2(B), or, though not shown in the drawing,may be extended straight radially, or bent at a right angle, or jogged;and the concave portion may be continuous, intermittent, or branched. Inaddition, this concave portion 3 may be formed also on the secondprocessing surface 2, or on both the first and second processingsurfaces 1 and 2. By forming the concave portion 13 as mentioned above,the micro-pump effect can be obtained so that the fluid to be processedmay be sucked into between the first and second processing surfaces 1and 2.

The base end of the concave portion 13 reaches preferably innercircumference of the first processing member 10. The front end of theconcave portion 13 extends in an outer circumferential direction (adownstream direction) of the first processing surface 1 with the depththereof (cross-sectional area) being gradually shallower as going fromthe base end toward the front end.

Between the front end of the concave portion 13 and the outer peripheryof the first processing surface 1 is arranged a flat surface 16 nothaving the concave portion 13.

When an opening d20 of the second introduction part d2 is arranged inthe second processing surface 2, the arrangement is done preferably at aposition opposite to the flat surface 16 of the first processing surface1 arranged at a position opposite thereto.

This opening d20 is arranged preferably in the downstream (outside inthis case) of the concave portion 13 of the first processing surface 1.The opening is arranged especially preferably at a position opposite tothe flat surface 16 located nearer to the outer diameter than a positionwhere the direction of flow upon introduction by the micro-pump effectis changed to the direction of a spiral and laminar flow formed betweenthe processing surfaces. Specifically, in FIG. 2(B), a distance n fromthe outermost side of the concave portion 13 arranged in the firstprocessing surface 1 in the radial direction is preferably about 0.5 mmor more. Especially in the case of separating microparticles from afluid, it is preferable that mixing of a plurality of fluids to beprocessed and separation of the nanoparticles therefrom be effectedunder the condition of a laminar flow. The Shape of the opening d20 maybe circular as shown in FIG. 2(B) and FIG. 3(B); or though not shown bya drawing, it may be a concentric circular ring with a ring-like diskshape which encloses the opening in the center of the processing surface2. If the opening is in the shape of the circular ring, this circularring opening may be continuous or discontinuous.

This second introduction part d2 may have directionality. For example,as shown in FIG. 3(A), the direction of introduction from the openingd20 of the second processing surface 2 is inclined at a predeterminedelevation angle (θ1) relative to the second processing surface 2. Theelevation angle (θ1) is set at more than 0° and less than 90°, and whenthe reaction speed is high, the angle (θ1) is preferably set in therange of 1° to 45°.

In addition, as shown in FIG. 3(B), introduction from the opening d20 ofthe second processing surface 2 has directionality in a plane along thesecond processing surface 2. The direction of introduction of thissecond fluid is in the outward direction departing from the center in aradial component of the processing surface and in the forward directionin a rotation component of the fluid between the rotating processingsurfaces. In other words, a predetermined angle (θ2) exists facing therotation direction R from a reference line g, which is the line to theoutward direction and in the radial direction passing through theopening d20. This angle (θ2) is also set preferably at more than 0° andless than 90°.

This angle (θ2) can vary depending on various conditions such as thetype of fluid, the reaction speed, viscosity, and the rotation speed ofthe processing surface. In addition, it is also possible not to give thedirectionality to the second introduction part d2 at all.

In the embodiment shown in FIG. 1, kinds of the fluid to be processedand numbers of the flow path thereof are set two respectively; but theymay be one, or three or more. In the embodiment shown in FIG. 1, thesecond fluid is introduced into between the processing surfaces 1 and 2from the introduction part d2; but this introduction part may bearranged in the first processing member 10 or in both. Alternatively, aplurality of introduction parts may be arranged relative to one fluid tobe processed. The opening for introduction arranged in each processingmember 10 and 20 is not particularly restricted in its form, size, andnumber; and these may be changed as appropriate. The opening forintroduction may be arranged just before the first and second processingsurfaces 1 and 2 or in the side of further upstream thereof.

In the apparatus mentioned above, the oxide microparticles or thehydroxide microparticles are separated by mixing the fluid that containsthe microparticle raw material solution in which at least onemicroparticle raw material is mixed therein with the fluid that containsthe microparticle-separating solution in the thin film fluid formedbetween the processing surfaces which are disposed in a position theyare faced with each other so as to be able to approach to and separatefrom each other, at least one of which rotates relative to the other.

The reaction accompanied with separation of the oxide microparticles orhydroxide microparticles takes place in the apparatus shown in FIG. 1under a forced and uniform mixing between the processing surfaces 1 and2 arranged opposite to each other so as to be able to approach to andseparate from each other, at least one of which rotates relative to theother.

Firstly, from one flow path, i.e., from the first introduction part dl,a first fluid containing a solution for separating microparticles isintroduced into between the processing surfaces 1 and 2 arrangedopposite to each other so as to be able to approach to and separate fromeach other, at least one of which rotates relative to the other, wherebyforming a first fluid film (thin film fluid) between these processingsurfaces.

Then, from a different flow path, i.e., from the second introducing partd2, a second fluid containing a microparticle raw material solution isintroduced directly into the first fluid film (thin film fluid) formedbetween the processing surfaces 1 and 2.

Meanwhile, because it is good enough only if the reaction could beeffected between the processing surfaces 1 and 2, as opposed to theforegoing method, a method wherein the second fluid is introduced fromthe first introduction part dl and a solution containing the first fluidis introduced from the second introduction part d2 may also be used.That is, the expression “first” or “second” for each fluid has a meaningfor merely discriminating an n^(th) fluid among a plurality of thefluids present; and therefore, a third or more fluids can also exist.

As mentioned above, the first fluid and the second fluid are mixedbetween the processing surfaces 1 and 2 whose distance is fixed by thepressure balance between the supply pressure of the fluid to beprocessed and the pressure applied between the rotating processingsurfaces so that the oxide microparticles or the hydroxidemicroparticles can be separated; and then, the dispersion solution ofthe oxide microparticles or the hydroxide microparticles can bedischarged from between the processing surfaces 1 and 2 as the fluidwhich contains the oxide microparticles or the hydroxide microparticles.

In the present invention, the isolatable oxide microparticles orhydroxide microparticles can be produced by contacting and acting themicroparticle-treating substance to the oxide microparticles or thehydroxide microparticles which are separated between the processingsurfaces 1 and 2. In addition, by contacting and acting themicroparticle-treating substance to the oxide microparticles or thehydroxide microparticles which are separated between the processingsurfaces 1 and 2, dispersibility of the oxide microparticles or thehydroxide microparticles can be controlled. Further, the isolatableoxide microparticles or hydroxide microparticles which are obtained bycontacting and acting the microparticle-treating substance to the oxidemicroparticles or the hydroxide microparticles which are separatedbetween the processing surfaces 1 and 2 tend to have a smaller particlediameter as compared with the oxide microparticles or the hydroxidemicroparticles which are obtained without contacting and acting thereofto the microparticle-treating substance.

The foregoing microparticle-treating substance is not particularlyrestricted; but an acidic substance or hydrogen peroxide may be used.The acidic substance is not particularly restricted, though anillustrative example thereof includes an inorganic acid such as aquaregia, hydrochloric acid, nitric acid, fuming nitric acid, sulfuricacid, fuming sulfuric acid, hydrogen fluoride, perchloric acid, andhexafluorosilicic acid, or a salt of them; and an organic acid such asformic acid, acetic acid, chloroacetic acid, dichloroacetic acid, oxalicacid, trifluoroacetic acid, trichioroacetic acid, and citric acid, or asalt of them. These substances may be used singly or as a mixture ofplurality of them.

The microparticle-treating substance is used preferably by mixing itwith a solvent, or more preferably it is used as amicroparticle-treating substance solution obtained by dissolving ormolecular-dispersing the substance in a solvent.

As to the solvent to dissolve or molecular-disperse themicroparticle-treating substance, the same solvents as those used todissolve or molecular-disperse the microparticle raw material may beused.

According to one embodiment of the present invention, the fluid whichcontains the microparticle-treating substance solution is introduced asthe third fluid into between the processing surfaces 1 and 2 afterseparating the oxide microparticles or the hydroxide microparticlesbetween the processing surfaces 1 and 2 which are disposed in a positionthey are faced with each other so as to be able to approach to andseparate from each other, at least one of which rotates relative to theother, and before discharging the dispersion solution of the oxidemicroparticles or the hydroxide microparticles from between theprocessing surfaces; by so doing, the dispersion solution of the oxidemicroparticles or the hydroxide microparticles can be mixed with thefluid which contains the microparticle-treating substance solutionbetween the processing surfaces 1 and 2 so that the oxide microparticlesor the hydroxide microparticles can be contacted with or acted to themicroparticle-treating substance between the processing surfaces 1 and2.

According to another embodiment of the present invention, the supplyingapparatus 51 of the fluid which contains the microparticle-treatingsubstance solution is arranged immediately after discharge of thedispersion solution of the oxide microparticles or the hydroxidemicroparticles from between the processing surfaces 1 and 2, thesemicroparticles being separated in a thin film fluid formed between theprocessing surfaces 1 and 2 of the apparatus explained above, in otherwords, near the fluid discharge part 51 b in the processing members 10and 20; and the fluid which contains the microparticle-treatingsubstance solution is sprayed or gradually added from this supplyingapparatus 51 thereby mixing the dispersion solution of the oxidemicroparticles or the hydroxide microparticles with the fluid whichcontains the microparticle-treating substance solution (see FIG. 4(A)).More specifically, the supplying apparatus 51 is provided with acircular flow path which is connected to source of the fluid whichcontains the microparticle-treating substance solution via the pump P.This circular flow path is arranged in the position facing to thedischarge part 51 b of the processing surfaces 1 and 2 (in this example,upper part); and in the lower position of the circular flow path isformed the opening 51 a. To carry out the present invention, preferablythis opening 51 a is formed of many small holes or is formed ofcontinuous slits so that the fluid which contains themicroparticle-treating substance solution may be supplied to anduniformly mixed with the dispersion solution which is discharged fromthe discharge part 51 b. Meanwhile, this discharge part 51 b is locatedin the most downstream side of the flow path which is forced by theprocessing surfaces 1 and 2 (in this example, the most outercircumference of the processing surfaces 1 and 2); and thus, the thinfilm fluid is released in this discharge part 51 b from this forceexerted by the processing surfaces 1 and 2 thereby discharging the fluidto a wider space of the flow path. Accordingly, the fluid which containsthe microparticle-treating substance solution is supplied to thedispersion solution which is discharged as the widely spreading solutionso that the microparticle-treating substance may be effectivelycontacted with and acted to the oxide microparticles or the hydroxidemicroparticles which are separated as mentioned above.

Alternatively, as shown in FIG. 4(B), the charging hole 53 to charge thefluid which contains the microparticle-treating substance solution maybe arranged in the flow path 52 thorough which the dispersion solutionof the discharged oxide microparticles or hydroxide microparticlespasses as a converged stream; and through this charging hole 53, thefluid which contains the microparticle-treating substance solution maybe charged. According to the method as mentioned above, there is a meritthat a step of separating the oxide microparticles or the hydroxidemicroparticles and a step of mixing the fluid which contains theseparated oxide microparticles or hydroxide microparticles with thefluid which contains the microparticle-treating substance solution canbe done continuously.

In addition, as mentioned before, the processing apparatus may beprovided with, in addition to the first introduction part d1 and thesecond introduction part d2, the third introduction part d3; and in thiscase, for example, each of the fluid which contains themicroparticle-separating solution as the first fluid, the fluid whichcontains the microparticle raw material solution as the second fluid,and the fluid which contains the microparticle-treating substancesolution as the third fluid may be introduced separately into theprocessing apparatus. In this case, the third introduction part d3 tointroduce the fluid which contains microparticle-treating substancesolution is arranged in the downstream side of the first introductionpart dl and the second introduction part d2, or in more detail, theopening d30 of the third introduction part d3 is arranged in thedownstream side of the opening d20 of the second introduction part; byso arranging, the microparticle-treating substance may be effectivelycontacted with and acted to the separated oxide microparticles orhydroxide microparticles (see, FIG. 4(C)).

By so doing, concentration and pressure of each of the fluids can becontrolled so that the separation reaction and production of theisolatable oxide microparticles and hydroxide microparticles may becontrolled more precisely. The same is applied if the fourth or moreintroduction parts are arranged; and by so doing, fluids to beintroduced into the processing apparatus may be subdivided.

In other embodiment, there may be mentioned; a method wherein themicroparticle-treating substance solution is charged into a containersuch as a beaker and a tank, and then, the dispersion solution of theoxide microparticles or the hydroxide microparticles which aredischarged from the processing surfaces 1 and 2 is recovered in thecontainer into which the microparticle-treating substance solution ischarged; and a method wherein the dispersion solution of the oxidemicroparticles or the hydroxide microparticles which are discharged fromthe processing surfaces 1 and 2 is recovered in an empty container, andthen, the microparticle-treating substance solution is charged into thecontainer which contains the recovered dispersion solution of the oxidemicroparticles or the hydroxide microparticles. There is no particularrestriction as to the stirring apparatus and the stirring method inmixing of the microparticle-treating substance solution with thedispersion solution of the oxide microparticles or the hydroxidemicroparticles in the container as mentioned above.

In the present invention, it is preferable that themicroparticle-treating substance be made uniformly contact with and actto the oxide microparticles or the hydroxide microparticles which areseparated between the processing surfaces 1 and 2; and thus, it ispreferable that a step of separating the oxide microparticles or thehydroxide microparticles between the processing surfaces 1 and 2 and astep of mixing the fluid which contains the microparticle-treatingsubstance solution with the fluid which contains the oxidemicroparticles or the hydroxide microparticles separated between theprocessing surfaces 1 and 2 be carried out within three seconds, or morepreferably within one second. In more detail, the time between when,into the thin film fluid that is formed between the processing surfaces1 and 2 by introducing, as the first fluid, any one of the fluid whichcontains the microparticle raw material solution and the fluid whichcontains the microparticle-separating solution from the firstintroduction part d1, one of the introduction path, any other one of thefluid which contains the microparticle raw material solution and thefluid which contains the microparticle-separating solution is introducedas the second fluid from the introduction part d2, the other flow path,and when the fluid which contains the oxide microparticles or thehydroxide microparticles which are separated between the processingsurfaces 1 and 2 is mixed with the fluid which contains themicroparticle-treating substance solution is preferably within threeseconds, or more preferably within one second.

Alternatively, within the range not adversely affecting separation ofthe oxide microparticles or the hydroxide microparticles, the fluidwhich contains the microparticle-treating substance solution may bemixed with any one of the fluid which contains the microparticle rawmaterial solution before separation of the oxide microparticles or thehydroxide microparticles and the fluid which contains themicroparticle-separating solution or both; by so doing, themicroparticle-treating substance may be contacted with and acted to theoxide microparticles or the hydroxide microparticles which are separatedbetween the processing surfaces 1 and 2. For example, as mentionedabove, the third introduction part d3 other than the first introductionpart d1 and the second introduction part d2 is arranged in theprocessing apparatus; and through each introduction part, as the firstfluid, any one of the fluid which contains the microparticle rawmaterial solution and the fluid which contains themicroparticle-separating solution, as the second fluid, any other one ofthe fluid which contains the microparticle raw material solution and thefluid which contains the microparticle-separating solution, and thethird fluid, the fluid which contains the microparticle-treatingsubstance solution may be separately introduced into the processingapparatus; by so doing, the fluid which contains themicroparticle-treating substance solution may be mixed with any one ofthe fluid which contains the microparticle raw material solution beforeseparation of the oxide microparticles or the hydroxide microparticlesand the fluid which contains the microparticle-separating solution orboth; and in this case, location of the opening d30 of the thirdintroduction part d3 of the fluid which contains themicroparticle-treating substance solution shall not be restricted.

In addition, state of the substance obtained by contacting and actingthe microparticle-treating substance with the separated oxidemicroparticles or hydroxide microparticles is not particularlyrestricted. For example, by contacting and acting themicroparticle-treating substance with hydroxide microparticles,isolatable oxide microparticles may be obtained or isolatablehydroxylated oxide microparticles may be obtained.

In addition, temperatures of the fluids to be processed such as thefirst, the second, and so on may be controlled; and temperaturedifference between the first fluid and the second fluid, or the like(namely, temperature difference among each of the supplied fluids to beprocessed) may be controlled either. In alternative practice, to controltemperature and temperature difference of each of the supplied fluids tobe processed, a mechanism with which temperature of each of the fluidsto be processed is measured (temperature of the fluid beforeintroduction to the processing apparatus, or in more detail, just beforeintroduction between the processing surfaces 1 and 2) so that each ofthe fluids to be processed may be heated or cooled may be installed.

EXAMPLES

Hereinafter, the present invention will be explained in more detail byExamples; but the present invention is not limited only to theseExamples.

It is to be noted here that the term “from the center” in the followingExamples means “from the first introduction part d1” of the processingapparatus shown in FIG. 1; the first fluid means the first fluid to beprocessed as described before; and the second fluid means the secondfluid to be processed that is introduced through the second introductionpart d2 of the processing apparatus shown in FIG. 1, as describedbefore.

In Examples, as shown in FIG. 1, a microparticle raw material solution(second fluid) is mixed with a microparticle-separating solution (firstfluid) by using a reaction apparatus with which these fluids areuniformly dispersed, stirred, and mixed in a thin film fluid formedbetween the processing surfaces 1 and 2 which are disposed in a positionthey are faced with each other so as to be able to approach to andseparate from each other, at least one of which rotates relative to theother, whereby effecting a separation reaction in the thin film fluid.Thereafter, a microparticle-treating substance solution (third fluid) ismixed therewith to produce isolatable oxide microparticles or hydroxidemicroparticles.

Examples 1 to 2 and Comparative Example 1

An aqueous ammonia solution (1% by mass) of the microparticle-separatingsolution as the first fluid with the liquid temperature of 80° C. wasintroduced from the center with supply pressure of 0.50 MPa and backpressure of 0.04 MPa and with rotation speed of 1700 rpm, while, as thesecond fluid, the microparticle raw material solution with the liquidtemperature of 25° C. which was obtained by dissolving zirconiumoxynitrate dihydrate (12.0% by mass) and yttrium nitrate nonahydrate(1.29% by mass) in water was introduced into between the processingsurfaces 1 and 2 at the rate of 5 mL/min. The first fluid and the secondfluid were mixed in the thin film fluid, whereby separating theyttria-stabilized zirconia hydrate microparticles between the processingsurfaces 1 and 2 and then discharging the particles as the dispersionsolution of the yttria-stabilized zirconia hydrate microparticles fromthe processing surfaces 1 and 2; and then, the discharged dispersionsolution of the yttria-stabilized zirconia hydrate microparticles wasmixed with the third fluid. As to this third fluid, themicroparticle-treating substance solution, an aqueous nitric acidsolution (1% by mass) or an aqueous hydrogen peroxide solution (1% bymass) was used. The dispersion solution of the dischargedyttria-stabilized zirconia hydrate microparticles was mixed with thethird fluid by gradually adding the third fluid to the position near thedischarge part 51 b outside the processing surfaces 1 and 2 at the rateof 50 mL/min and with the liquid temperature of 80° C., therebyeffecting mixing of these fluids at the position near the discharge part51 b and in the flow path 52 at which the discharged solution wasconverged. The time between when the dispersion solution of theyttria-stabilized zirconia hydrate microparticles was discharged fromthe processing surfaces 1 and 2 and when it was mixed with the thirdfluid was approximately 0.5 seconds. The time between when the secondfluid was introduced between the processing surfaces 1 and 2 and whenthe dispersion solution of the yttria-stabilized zirconia hydratemicroparticles was discharged from the processing surfaces 1 and 2 wasapproximately 0.3 seconds for most of the microparticles; and thus, thetime between when the second fluid was introduced between the processingsurfaces 1 and 2 and when the dispersion solution of theyttria-stabilized zirconia hydrate microparticles which were dischargedfrom the processing surfaces 1 and 2 was mixed with the third fluid waswithin one second. Meanwhile, respective liquid temperatures of thefirst to the third fluids were measured at the position just before therespective fluids were introduced into the processing apparatus.

To remove impurities from the mixture solution of the dischargeddispersion solution of the yttria-stabilized zirconia hydratemicroparticles and the third fluid, the yttria-stabilized zirconiahydrate microparticles were loosely aggregated, and then, theyttria-stabilized zirconia hydrate microparticles were spun down byusing a centrifugal separator (x8000 G); and after the supernatant wasremoved, the yttria-stabilized zirconia hydrate microparticles wereredispersed by adding pure water and then spun down again by using acentrifugal separator. This washing operation was repeated for threetimes; and then, a finally obtained paste of the yttria-stabilizedzirconia hydrate microparticles was dried at 60° C. under vacuum of −0.1MPaG to obtain dried powders of the yttria-stabilized zirconia hydratemicroparticles. Further, the obtained dried powders of theyttria-stabilized zirconia hydrate microparticles were subjected to theheat treatment at 400° C. for 4 hours. The results of the experiments byusing the changed third fluid are shown in Table 1. For comparison withExamples 1 to 2, Comparative Example 1 was done as to theyttria-stabilized zirconia hydrate microparticles and theyttria-stabilized zirconia microparticles which were prepared withoutmixing the third fluid with the dispersion solution of theyttria-stabilized zirconia hydrate microparticles which were dischargedfrom between the processing surfaces 1 and 2 in the same methods asExamples 1 to 2. TEM pictures of the yttria-stabilized zirconia hydratemicroparticles before the heat treatment and TEM pictures of theyttria-stabilized zirconia microparticles after the heat treatment,obtained in Examples 1 to 2 and Comparative Example 1, are shown in FIG.5 to FIG. 7. The dispersibility in Table 1 was judged to be “Good” whenthe yttria-stabilized zirconia hydrate microparticles or theyttria-stabilized zirconia microparticles were observed as dispersedloose particles in the TEM picture, and judged to be “Poor” when theywere observed otherwise. A particle diameter of the dispersedmicroparticles shown in Table 1 was confirmed by observation with theTEM picture. From the TEM pictures of FIG. 5 to FIG. 7, it was confirmedthat microparticles which were obtained by using the aqueous nitric acidsolution or the aqueous hydrogen peroxide solution as the third fluid inExample 1 or Example 2 were dispersed till primary particles, oncontrary to Comparative Example 1 in which the third fluid was not used.From Table 1 and FIG. 5 to FIG. 7, it was found that, by using theaqueous hydrogen peroxide solution or the aqueous nitric acid solutionas the acidic substance, the dispersibility of the yttria-stabilizedzirconia hydrate microparticles before the heat treatment and theyttria-stabilized zirconia microparticles obtained after the heattreatment could be improved.

TABLE 1 Dispersed particle diameter (TEM diameter) (nm) DispersibilityBefore After Before After heat heat heat heat Third fluid treatmenttreatment treatment treatment Example 1 Aqueous 2 to 10 2 to 10 GoodGood nitric acid solution (1% by mass) Example 2 Aqueous 2 to 30 2 to 10Good Good hydrogen peroxide solution (1% by mass) Comparative None 100or 100 or Poor Poor Example 1 more more

Examples 3 to 4 and Comparative Example 2

An aqueous sodium hydroxide solution (1% by mass) of themicroparticle-separation solution as the first fluid with the liquidtemperature of 80° C. was introduced from the center at the rate of 250mL/min with supply pressure of 0.50 MPa and back pressure of 0.04 MPaand with rotation speed of 500 rpm, while, as the second fluid, themicroparticle raw material solution with the liquid temperature of 25°C. which was obtained by dissolving magnesium chloride hexahydrate(10.0% by mass) in water was introduced into between the processingsurfaces 1 and 2 at the rate of 10 mL/min. The first fluid and thesecond fluid were mixed in the thin film fluid, whereby separating themagnesium hydroxide microparticles between the processing surfaces 1 and2 and discharging the particles from the processing surfaces 1 and 2 asthe dispersion solution of the magnesium hydroxide microparticles.Thereafter, the discharged dispersion solution of the magnesiumhydroxide microparticles was mixed with the third fluid; and then, theywere stirred at 65° C. for two hours. This stirring treatment was doneby using Clearmix 2.2S (manufactured by M Technique Co., Ltd.) with therotation speed of 20000 rpm. As to this third fluid, themicroparticle-treating substance solution, aqueous hydrogen peroxidesolutions (0.5 to 1.0% by mass) were used. The dispersion solution ofthe discharged magnesium hydroxide microparticles was mixed with thethird fluid by gradually adding the third fluid to the position near thedischarge part 51 b outside the processing surfaces 1 and 2 at the rateof 50 mL/min and with the liquid temperature of 80° C., therebyeffecting mixing of these fluids at the position near the discharge part51 b and in the flow path 52 at which the discharged solution wasconverged. The time between when the dispersion solution of themagnesium hydroxide microparticles was discharged from the processingsurfaces 1 and 2 and when it was mixed with the third fluid wasapproximately 0.5 seconds. The time between when the second fluid wasintroduced between the processing surfaces 1 and 2 and when thedispersion solution of the magnesium hydroxide microparticles wasdischarged from the processing surfaces 1 and 2 was approximately 0.3seconds for most of the microparticles; and thus, the time between whenthe second fluid was introduced between the processing surfaces 1 and 2and when the dispersion solution of the magnesium hydroxidemicroparticles which were discharged from the processing surfaces 1 and2 was mixed with the third fluid was within one second. Meanwhile,respective liquid temperatures of the first to the third fluids weremeasured at the position just before the respective fluids wereintroduced into the processing apparatus.

To remove impurities from the mixture solution of the third fluid andthe dispersion solution of the magnesium hydroxide microparticles afterthe stirring treatment, the magnesium hydroxide microparticles wereloosely aggregated, and then, the magnesium hydroxide microparticleswere spun down by using a centrifugal separator (x8000 G); and after thesupernatant was removed, the magnesium hydroxide microparticles wereredispersed by adding pure water and then spun down again by using acentrifugal separator. This washing operation was repeated for threetimes; and then, a finally obtained paste of the magnesium hydroxidemicroparticles was dried at 60° C. under vacuum of −0.1 MPaG to obtaindried powders of the magnesium hydroxide microparticles. Further, theobtained dried powders of the magnesium hydroxide microparticles weresubjected to the heat treatment at 500° C. for 4 hours. As a result ofmeasurement of the X-ray diffraction (XRD) of the dried microparticlepowders before and after the heat treatment, it was confirmed that themagnesium hydroxide microparticles were changed to the magnesium oxideafter the heat treatment.

The results of the experiments by changing the hydrogen peroxideconcentration in the third fluid are shown in Table 2 (Examples 3 to 4).For comparison with Examples 3 to 4, Comparative Example 2 was done asto the magnesium hydroxide microparticles and the magnesium oxidemicroparticles which were prepared without mixing the third fluid withthe dispersion solution of the magnesium hydroxide microparticles whichwere discharged from between the processing surfaces 1 and 2 in the samemethods as Examples 3 to 4. TEM pictures of the magnesium oxidemicroparticles after the heat treatment in Example 3 and ComparativeExample 2 are shown in FIG. 8 to FIG. 9. The dispersibility in Table 2was judged to be “Good” when the magnesium hydroxide microparticles orthe magnesium oxide microparticles were observed as dispersed looseparticles in the TEM picture, and judged to be “Poor” when they wereobserved otherwise. From Table 2 and FIG. 8 to FIG. 9, it was foundthat, by using the aqueous hydrogen peroxide solution as the thirdfluid, the dispersibility of the magnesium hydroxide microparticlesbefore the heat treatment and the magnesium oxide microparticles afterthe heat treatment could be improved. In addition, the dispersibility ofthe magnesium hydroxide microparticles before the heat treatment and themagnesium oxide microparticles after the heat treatment could becontrolled by mixing the discharged dispersion solution of the magnesiumhydroxide microparticles with the third fluid of the aqueous hydrogenperoxide solution thereby making the magnesium hydroxide microparticlescontact with and act to hydrogen peroxide. As to concentration ofhydrogen peroxide in the aqueous hydrogen peroxide solution, even if acomparatively dilute aqueous hydrogen peroxide solution was used formixing with the discharged dispersion solution of the magnesiumhydroxide microparticles, the dispersibility of the magnesium hydroxidemicroparticles before the heat treatment and the magnesium oxidemicroparticles after the heat treatment could be controlled. From theresults as shown above, it was confirmed that the isolatable magnesiumhydroxide microparticles and magnesium oxide microparticles can beobtained by mixing the dispersion solution of the magnesium hydroxidemicroparticles which are discharged from the processing surfaces 1 and 2with the aqueous hydrogen peroxide solution thereby making the magnesiumhydroxide microparticles contact with and act to hydrogen peroxide.

TABLE 2 Dispersibility Before heat After heat Third fluid treatment: Mg(OH)₂ treatment: MgO Example 3 Aqueous hydrogen Good Good peroxidesolution (0.5% by mass) Example 4 Aqueous hydrogen Good Good peroxidesolution (1.0% by mass) Comparative None Poor Poor Example 2

Examples 5 to 6 and Comparative Examples 3 to 5

Microparticle-separation solution of an aqueous ammonia solution (1% bymass), isopropyl alcohol (IPA), or acetone was introduced as the firstfluid from the center with supply pressure of 0.50 MPa and back pressureof 0.04 MPa and with rotation speed of 1700 rpm, while, as the secondfluid, the microparticle raw material solution of an aqueous titanylsulfate solution (10% by mass) or an aqueous titanium tetrachloridesolution (10% by mass) with the liquid temperature thereof being 25° C.was introduced into between the processing surfaces 1 and 2 at the rateof 5 mL/min. The first fluid and the second fluid were mixed in the thinfilm fluid, whereby separating the titanium dioxide microparticlesbetween the processing surfaces 1 and 2 and discharging the particles asthe dispersion solution of the titanium dioxide microparticles from theprocessing surfaces 1 and 2. Thereafter, the discharged dispersionsolution of the titanium dioxide microparticles was mixed with the thirdfluid; and then, they were allowed to stand or stirred at 65 to 80° C.for four hours. This stirring treatment was done by using a magneticstirrer with the rotation speed of 600 rpm in a water bath. As to thisthird fluid of the microparticle-treating substance solution, an aqueousnitric acid solution (1% by mass) was used. In example 5, the dischargeddispersion solution of the titanium dioxide microparticles was mixedwith the third fluid by gradually adding the third fluid to the positionnear the discharge part 51 b outside the processing surfaces 1 and 2 atthe rate of 50 mL/min and with the liquid temperature of 80° C., therebyeffecting mixing of these fluids at the position near the discharge part51 b and in the flow path 52 at which the discharged solution wasconverged. In Example 6, into the third fluid which was previouslyprepared in a plastic container was continuously mixed the dispersionsolution of the titanium dioxide microparticles discharged from theprocessing surfaces 1 and 2 within 0.6 seconds after discharge. The timebetween when the dispersion solution of the titanium dioxidemicroparticles was discharged from the processing surfaces 1 and 2 andwhen it was mixed with the third fluid was approximately 0.6 seconds.The time between when the second fluid was introduced between theprocessing surfaces 1 and 2 and when the dispersion solution of thetitanium dioxide microparticles was discharged from the processingsurfaces 1 and 2 was approximately 0.3 seconds for most of themicroparticles; and thus, the time between when the second fluid wasintroduced between the processing surfaces 1 and 2 and when thedispersion solution of the titanium dioxide microparticles which weredischarged from the processing surfaces 1 and 2 was mixed with the thirdfluid was within one second. Meanwhile, respective liquid temperaturesof the first to the third fluids were measured at the position justbefore the respective fluids were introduced into the processingapparatus; and the liquid temperature of the first fluid is shown inTable 3.

To remove impurities from the mixture solution of the dischargeddispersion solution of the titanium dioxide microparticles and the thirdfluid, the titanium dioxide microparticles were loosely aggregated, andthen, the titanium dioxide microparticles were spun down by using acentrifugal separator (x8000 G); and after the supernatant was removed,the titanium dioxide microparticles were redispersed by adding purewater and then spun down again by using a centrifugal separator. Thiswashing operation was repeated for three times; and then, a finallyobtained paste of the titanium dioxide microparticles was dried at 60°C. under vacuum of −0.1 MPaG.

The results of the experiments by changing the conditions are shown inTable 3. For comparison with Examples 5 to 6, Comparative Examples 3 to5 were done as to the titanium dioxide microparticles which wereprepared without mixing the third fluid with the dispersion solution ofthe titanium dioxide microparticles which were discharged from theprocessing surfaces 1 and 2 in the same methods as Examples 5 to 6. Thedispersibility in Table 3 was judged to be “Good” when the titaniumdioxide microparticles were observed as dispersed loose particles in theTEM picture, and judged to be “Poor” when they were observed otherwise.In the item of “Primary particle diameter” in Table 3, the primaryparticle diameter obtained by the TEM observation was recorded. In FIG.10, the TEM picture of the titanium dioxide microparticles obtained inExample 6 is shown. From Table 3 and FIG. 10, it was found that, byusing the aqueous nitric acid solution as the acidic substance in thethird fluid, the dispersibility of the titanium dioxide microparticlescould be improved. In addition, it was found that, the dispersibility ofthe titanium dioxide microparticles could be improved by using theaqueous nitric acid solution as the acidic substance in the third fluidregardless of the kind of the first fluid and the second fluid. Further,it was found that, the dispersibility of the titanium dioxidemicroparticles could be improved by using the aqueous nitric acidsolution as the acidic substance in the third fluid regardless of thetreatment methods, i.e., whether the mixed solution of the dischargeddispersion solution of the titanium dioxide microparticles and the thirdfluid was allowed to stand or stirred. From the results of all ofExamples and Comparative Examples, it was confirmed that thedispersibility of oxide microparticles or hydroxide microparticlesbefore and after the heat treatment can be controlled and thatisolatable oxide microparticles or hydroxide microparticles can beobtained if, immediately after the oxide microparticles or hydroxidemicroparticles which are separated between the processing surfaces 1 and2 are discharged from the processing surfaces 1 and 2 as the dispersionsolution of the oxide microparticles or hydroxide microparticles, thedispersion solution of the oxide microparticles or hydroxidemicroparticles is mixed with the microparticle-treating substancesolution thereby making the oxide microparticles or the hydroxidemicroparticles contact with and act to the microparticle-treatingsubstance.

TABLE 3 Primary Temperature Standing particle of first or diameter Firstfluid fluid (° C.) Second fluid Third fluid stirring (nm) DispersibilityExample 5 IPA 65 Aqueous Aqueous Stirring 20 Good titanium nitric acidtetrachloride solution solution (1% by mass) (10% by mass) Example 6Aqueous 25 Aqueous Aqueous standing  5 Good ammonia titanyl nitric acidsolution sulfate solution (1% by mass) solution (1% by mass) (10% bymass) Comparative IPA 65 Aqueous None standing 10 Poor Example 3titanium tetrachloride solution (10% by mass) Comparative Aqueous 25Aqueous None No  5 Poor Example 4 ammonia titanyl treatment solutionsulfate (1% by mass) solution (10% by mass) Comparative Acetone 65Aqueous None Stirring 30 Poor Example 5 titanium tetrachloride solution(10% by mass)

EXPLANATION OF REFERENCE NUMERALS

-   1 first processing surface-   2 second processing surface-   10 first processing member-   11 first holder-   20 second processing member-   21 second holder-   51 a opening-   51 b discharge part-   d1 first introduction part-   d2 second introduction part-   d20 opening-   d30 opening-   P fluid pressure imparting mechanism

The invention claimed is:
 1. A method for producing isolatable oxidemicroparticles or hydroxide microparticles, wherein each of (I) amicroparticle raw material solution which is obtained by mixing at leastone microparticle raw material with a solvent, (II) amicroparticle-separating solution, and (III) a microparticle-treatingsubstance solution which is obtained by mixing at least onemicroparticle-treating substance with a solvent is prepared, wherein themethod comprises: (IV) a step of separating oxide microparticles orhydroxide microparticles, wherein at least two fluids to be processedare used: out of them, at least one fluid is the fluid which containsthe microparticle raw material solution and at least one fluid otherthan the microparticle raw material solution is the fluid which containsthe microparticle-separating solution, wherein the fluid which containsthe microparticle raw material solution is mixed with the fluid whichcontains the microparticle-separating solution in a thin film fluidformed between at least two processing surfaces which are disposed in aposition they are faced with each other so as to be able to approach toand separate from each other, at least one of which rotates relative tothe other, and (V) a step of mixing a fluid which contains the oxidemicroparticles or the hydroxide microparticles separated in the step(IV) with the fluid which contains the microparticle-treating substancesolution, wherein the microparticle-treating substance is a substancewhich controls dispersibility of the said separated oxidemaicroparticles or hydroxide microparticles.
 2. The method for producingisolatable oxide microparticles or hydroxide microparticles according toclaim 1, wherein any one of the fluid which contains the microparticleraw material solution and the fluid which contains themicroparticle-separating solution passes between the processing surfaceswith forming the thin film fluid, a separate introduction pathindependent of a flow path through which any one of the fluids passes isarranged, at least any one of the at least two processing surfaces isprovided with an opening to the introduction path, any other one of thefluid which contains the microparticle raw material solution and thefluid which contains the microparticle-separating solution is introducedbetween the processing surfaces through the opening, whereby mixing thefluid which contains the microparticle raw material solution with thefluid which contains the microparticle-separating solution in the thinfilm fluid.
 3. The method for producing isolatable oxide microparticlesor hydroxide microparticles according to claim 1, wherein the methodcomprises: a step of separating oxide microparticles or hydroxylatedoxide microparticles by mixing the fluid which contains themicroparticle raw material solution with the fluid which contains themicroparticle-separating solution in the thin film fluid formed betweenat least two processing surfaces which are disposed in a position theyare faced with each other so as to be able to approach to and separatefrom each other, at least one of which rotates relative to the other,and a step of mixing the fluid which contains the oxide microparticlesor the hydroxide microparticles separated in the above-mentioned stepwith the fluid which contains the microparticle-treating substancesolution, wherein these steps are carried out continuously.
 4. Themethod for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 3, wherein at least any one of the atleast two processing surfaces is provided with an opening to introducethe fluid which contains the microparticle-treating substance solutionbetween the processing surfaces, the fluid which contains themicroparticle raw material solution is mixed with the fluid whichcontains the microparticle-separating solution in the thin film fluid toseparate oxide microparticles or hydroxide microparticles, andthereafter, the microparticle-treating substance is contacted with andacted to the separated oxide microparticles or hydroxide microparticlesin the thin film fluid.
 5. The method for producing isolatable oxidemicroparticles or hydroxide microparticles according to claim 3, whereinan opening to supply the fluid which contains the microparticle-treatingsubstance solution is arranged in a position to face a discharge part ofthe at least two processing surfaces, the fluid which contains themicroparticle raw material solution is mixed with the fluid whichcontains the microparticle-separating solution in the thin film fluid toseparate the oxide microparticles or the hydroxide microparticlesthereby discharging the fluid which contains the oxide microparticles orthe hydroxide microparticles through the discharge part, and immediatelythereafter, the microparticle-treating substance is contacted with andacted to the separated oxide microparticles or hydroxide microparticles.6. The method for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 1, wherein a step of mixing the fluidwhich contains the separated oxide microparticles or hydroxidemicroparticles with the fluid which contains the microparticle-treatingsubstance solution is carried out within one second after the step ofseparating the oxide microparticles or the hydroxide microparticles. 7.The method for producing isolatable oxide microparticle or hydroxidemicroparticle according to claim 1, wherein dispersibility of the oxidemicroparticles or the hydroxide microparticles is controlled bycontrolling concentration of the microparticle-treating substance in themicroparticle-treating substance solution that is contacted with andacted to the separated oxide microparticles or hydroxide microparticles.8. The method for producing isolatable oxide microparticles or hydroxidemicroparticles according to claim 1, wherein the microparticle-treatingsubstance is an acidic substance or hydrogen peroxide.
 9. The method forproducing isolatable oxide microparticles or hydroxide microparticlesaccording to claim 2, wherein the method comprises: a step of separatingoxide microparticles or hydroxylated oxide microparticles by mixing thefluid which contains the microparticle raw material solution with thefluid which contains the microparticle-separating solution in the thinfilm fluid formed between at least two processing surfaces which aredisposed in a position they are faced with each other so as to be ableto approach to and separate from each other, at least one of whichrotates relative to the other, and a step of mixing the fluid whichcontains the oxide microparticles or the hydroxide microparticlesseparated in the above-mentioned step with the fluid which contains themicroparticle-treating substance solution, wherein these steps arecarried out continuously.
 10. The method for producing isolatable oxidemicroparticles or hydroxide microparticles according to claim 2, whereina step of mixing the fluid which contains the separated oxidemicroparticles or hydroxide microparticles with the fluid which containsthe microparticle-treating substance solution is carried out within onesecond after the step of separating the oxide microparticles or thehydroxide microparticles.
 11. The method for producing isolatable oxidemicroparticles or hydroxide microparticles according to claim 3, whereina step of mixing the fluid which contains the separated oxidemicroparticles or hydroxide microparticles with the fluid which containsthe microparticle-treating substance solution is carried out within onesecond after the step of separating the oxide microparticles or thehydroxide microparticles.
 12. The method for producing isolatable oxidemicroparticles or hydroxide microparticles according to claim 4, whereina step of mixing the fluid which contains the separated oxidemicroparticles or hydroxide microparticles with the fluid which containsthe microparticle-treating substance solution is carried out within onesecond after the step of separating the oxide microparticles or thehydroxide microparticles.
 13. The method for producing isolatable oxidemicroparticles or hydroxide microparticles according to claim 5, whereina step of mixing the fluid which contains the separated oxidemicroparticles or hydroxide microparticles with the fluid which containsthe microparticle-treating substance solution is carried out within onesecond after the step of separating the oxide microparticles or thehydroxide microparticles.
 14. The method for producing isolatable oxidemicroparticle or hydroxide microparticle according to claim 2, whereindispersibility of the oxide microparticles or the hydroxidemicroparticles is controlled by controlling concentration of themicroparticle-treating substance in the microparticle-treating substancesolution that is contacted with and acted to the separated oxidemicroparticles or hydroxide microparticles.
 15. The method for producingisolatable oxide microparticle or hydroxide microparticle according toclaim 3, wherein dispersibility of the oxide microparticles or thehydroxide microparticles is controlled by controlling concentration ofthe microparticle-treating substance in the microparticle-treatingsubstance solution that is contacted with and acted to the separatedoxide microparticles or hydroxide microparticles.
 16. The method forproducing isolatable oxide microparticle or hydroxide microparticleaccording to claim 4, wherein dispersibility of the oxide microparticlesor the hydroxide microparticles is controlled by controllingconcentration of the microparticle-treating substance in themicroparticle-treating substance solution that is contacted with andacted to the separated oxide microparticles or hydroxide microparticles.17. The method for producing isolatable oxide microparticle or hydroxidemicroparticle according to claim 5, wherein dispersibility of the oxidemicroparticles or the hydroxide microparticles is controlled bycontrolling concentration of the microparticle-treating substance in themicroparticle-treating substance solution that is contacted with andacted to the separated oxide microparticles or hydroxide microparticles.18. The method for producing isolatable oxide microparticle or hydroxidemicroparticle according to claim 6, wherein dispersibility of the oxidemicroparticles or the hydroxide microparticles is controlled bycontrolling concentration of the microparticle-treating substance in themicroparticle-treating substance solution that is contacted with andacted to the separated oxide microparticles or hydroxide microparticles.19. The method for producing isolatable oxide microparticles orhydroxide microparticles according to claim 2, wherein themicroparticle-treating substance is an acidic substance or hydrogenperoxide.
 20. The method for producing isolatable oxide microparticlesor hydroxide microparticles according to claim 3, wherein themicroparticle-treating substance is an acidic substance or hydrogenperoxide.